Disposable needle-free injection apparatus and method

ABSTRACT

One form of the invention provides a needle-free injection system including the following components: a nozzle portion having a glass wall defining a drug storage space, and an injection wall defining a drug injection space, the injection wall being aligned with the glass wall and defining a plurality of drug bypass conduits disposed adjacent a forward end of the drug injection space; an injection orifice defined at the forward end of the injection space; a drug plunger defining a rearward end of the storage space; a portion of dried drug initially disposed between the storage space and the injection space, and being displaceable into the injection space adjacent the bypass conduits; and a pierceable gas cartridge for providing injection power to the drug plunger.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of the following applications: U.S. Ser. No.09/799,787 filed Mar. 5, 2001 now U.S. Pat. No. 6,471,669, forDISPOSABLE NEEDLE-FREE INJECTION APPARATUS AND METHOD and InternationalApplication No. PCT/US02/07299, filed Mar. 5, 2002 for DISPOSABLENEEDLE-FREE INJECTION APPARATUS AND METHOD. The subject matter of eachapplication is incorporated herein by this reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a single-use disposableneedle-free (or needleless) jet injection device. Specifically, thisinvention relates to such a jet injection device that comprises ahand-held injector having a pre-filled drug cartridge sealingly carryinginjectable drug, a sealed cylinder of pressurized gas, a piercingmechanism for penetrating the gas cylinder, and a trigger device forreleasing the discharge mechanism. The device is smaller and has fewerparts than prior disposable systems, and can be easily assembled andfilled using automated equipment.

RELATED TECHNOLOGY

Needle-free or needleless hypodermic jet injection devices have been incommercial use for over 40 years. A number of these devices have usedpressurized gas to power a hypodermic jet injection. The relatedtechnology includes a number of teachings for gas-powered injectiondevices, including: U.S. Pat. No. 4,596,556, issued to J. Thomas Morrow,et al.; U.S. Pat. No. 4,913,699, issued to James S. Parsons, and U.S.Pat. No. 5,730,723, issued to Thomas P. Castellano, et al. WIPOpublication WO 97/37705 also discloses a gas powered disposableneedle-free hypodermic jet injector.

The Morrow, et al. '556 patent is believed to teach a reusablehypodermic jet injection device in which a housing receives a shell orcartridge having a bore leading to a discharge aperture. Within the boreis received both a plunger sealingly engaging the bore, and apressurized gas cylinder that rests against the plunger. The injectiondevice includes a ram having a penetrating tip confronting a penetrablewall section and seal of the gas cylinder, and a discharge mechanism fordriving the ram through the penetrable wall section of the gas cylinderwhen a trigger device is released. Discharge of the pressurized gas fromthe cylinder drives the plunger to effect a jet injection, and alsodrives the seal of the gas cylinder to effect resetting of the dischargemechanism. The shell with its plunger and spent gas cylinder isdiscarded after an injection; a new shell, pre-filled with medicationand with a new gas cylinder, is used for each injection.

The Parsons '699 patent is believed to teach a single-use jet injectorthat is discarded after one use. This injector is believed to have abody with a pair of gas chambers separated by a breakable valve. One ofthe gas chambers contains a pressurized gas, while the other chamber issealingly bounded by a piston that drives a plunger. The plungersealingly bounds a chamber into which a dose of medication is loaded bythe user before the injection. This medication dose chamber leads to aninjection orifice so that when the valve is broken, the piston andplunger are moved by pressurized gas communicated to the second chamber,and the plunger drives the medication forcefully out of the injectionorifice to form an injection jet. After a single use, the device isdiscarded.

The Castellano '723 patent, which was issued in 1998 and which does notcite the earlier Parsons '699 patent, is believed to teach substantiallythe same subject matter as Parsons et al.

WIPO publication WO 97/37705 published pursuant to a Patent CooperationTreaty (PCT) application for joint inventors Terence Weston and PixeyThornlea, is believed to disclose a disposable hypodermic jet injectorin which the device is powered by a gas pressure spring of the typecommon in the tool and die art as a substitute for the conventionalmetal spring-powered ejector pin. In the Weston device, the ram of thegas pressure spring is held in a contracted position by a triggermechanism. When the trigger mechanism is released, the gas pressurespring is supposed to expand and drive a piston sealingly received in abore and leading to a fine-dimension orifice to produce a jet hypodermicinjection from liquid held in the bore ahead of the piston.

The Weston device is thought to have several deficiencies such asdifficult and costly manufacturing and sterilization processes becausethe pressurized gas and a drug dose need to be contained in the samepackage, and a possible inability to endure long-term storage whilestill retaining the gas pressure in the gas spring. In other words, thegas pressure spring of the Weston device contains only a small quantityof gas, and depends upon the sealing relationship of the ram of thisspring with a cylinder within which the ram is movably and sealinglyreceived in order to retain this gas pressure. Even a small amount ofgas leakage over time will be enough to render this injectorinoperative.

It also is known in this art to provide a needle-free injection systemhaving two plungers that are initially spaced adjacent either end of aglass drug storage sleeve, with liquid drug being disposed between theplungers within the sleeve. Such a system also includes a plastic drugstorage chamber disposed coaxially with and forwardly of the glass drugstorage sleeve. The forward end of the plastic drug chamber terminatesin an injection orifice. The plastic drug chamber includes an enlargedportion that permits drug to flow past the forward plunger when thatplunger is aligned with the enlarged portion.

In this earlier system, axial force is exerted on the rear plungerimmediately prior to injection. Because liquid drug is disposed in thespace between the plungers, the plungers move in unison in a forwarddirection until the forward plunger is aligned with the enlargedportion. At that point, the continued forward travel of the rearwardplunger forces liquid drug around the forward plunger until all of thedrug is disposed in the plastic drug chamber forward of both plungers,which are now in abutment. The unit thus is ready for actuation.

When the unit is actuated the plungers both exert a forward axial force,causing liquid drug to be directed out of the injection orifice and intothe patient.

SUMMARY OF THE INVENTION

One form of the invention provides a needle-free injection systemincluding the following components: a nozzle portion having a glass walldefining a drug storage space, and an injection wall defining a druginjection space, the injection wall being coaxial with the glass walland defining a plurality of drug bypass conduits disposed adjacent aforward end of the drug injection space; a body portion mounted to thenozzle portion such that relative axial movement may be effected betweenthe portions; an injection orifice defined at the forward end of theinjection space; a drug plunger defining a rearward end of the storagespace; a drug plug initially disposed between the storage space and theinjection space, and being displaceable into the injection spaceadjacent the bypass conduits; and a pierceable gas cartridge forproviding injection power to the drug plunger.

Another form the invention takes is a needle-free injection systemincluding the following components: a nozzle portion defining aforwardly-facing injection orifice; a body portion mounted to the nozzleportion, the portions being displaceable toward each other to preparethe system for actuation; and a safety tab for preventing actuationprior to the time that relative displacement is effected between thenozzle portion and the body portion, the safety tab being frangiblymounted to one of the body portion or the nozzle portion and including acontact part, the safety tab to be contacted and broken when theportions are displaced toward each other.

Yet another form the invention takes is a method for preparing aneedle-free injection unit for injection, comprising the followingsteps: providing a storage compartment for liquid drug; positioning aninjection orifice forwardly of the storage compartment, through whichthe liquid drug is selectively injected into the patient; providing apressurized, pierceable gas storage cartridge with a system forconveying pressure to the storage compartment when the cartridge ispierced; positioning a seal between the cartridge and the storagecompartment to prevent gas pressure from reaching the storagecompartment after the cartridge is pierced, but prior to actuation ofthe unit, the seal being positioned such that the piercing of thecartridge provides axial pressure on the seal; providing a triggerhaving a roller positioned such that when axial pressure is provided onthe trigger, an outward force is exerted on the trigger; and positioninga trigger actuator outwardly of the trigger to prevent the trigger frommoving outwardly until the unit is actuated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a first embodiment of the presentinvention, showing the unit ready for shipping to the patient;

FIG. 2 is a side elevation sectional view taken along line 2—2 of FIG.1;

FIG. 3 is a side elevation sectional view taken along line 3—3 of FIG.1, at 90° from the view of FIG. 2;

FIG. 4 is a side elevation sectional view corresponding to FIG. 3 exceptthat the threaded nozzle portion is shown to be about half of the waythreaded into the body portion, and the drug plunger and drug plug areshown shifted forwardly, with the drug plug seated in the forward end ofthe plastic drug chamber;

FIG. 5 is a view corresponding to FIG. 4 except that the gas cartridgeis shown to be pierced as a result of the nozzle portion being turnedentirely into the body portion; the apparatus is ready for injection;

FIG. 6A is an end elevation sectional view taken along line 6A—6A ofFIG. 5;

FIG. 6B is an end elevation sectional view taken along line 6B—6B ofFIG. 5;

FIG. 6C is an end elevation sectional view taken along line 6C—6C ofFIG. 5;

FIG. 7 is a view corresponding to FIG. 5 except that liquid drug has nowbeen injected into the patient, and the apparatus is ready for disposal;

FIG. 8 is an exploded view of the embodiment of FIGS. 1-7;

FIG. 8A is an enlarged, schematic, fragmentary side elevation sectionalview showing the leg and nib construction of the embodiment of FIGS. 1-8that provides a capability of holding the nozzle portion in engagementwith the body portion during storage and shipping;

FIG. 9 is a schematic, fragmentary plan view of one of the safety tabsincluded in the embodiment of FIGS. 1-8;

FIG. 10 is a side elevation sectional view taken along line 10—10 ofFIG. 9;

FIG. 11 is a fragmentary, end elevation sectional view taken along line11—11 of FIG. 9;

FIG. 12 is a side elevation sectional view of a second embodiment,designed for intradermal injection, showing the unit ready for shipping;

FIG. 13 is a fragmentary, exploded view of a third embodiment, showingball bearings used in place of the trigger elements;

FIG. 14 is a fragmentary, side elevation sectional view of a fourthembodiment, showing the use of a smaller O-ring seal to reduce theamount of axial force on the seal;

FIG. 15 is a side elevation view of a fifth embodiment, showing only theproximal end of the nozzle portion, the nozzle portion threads includinga pair of slots;

FIG. 16 is an end elevation sectional view taken along line 16—16 ofFIG. 15, showing one of the two slots;

FIG. 17 is a fragmentary side elevation view of the body portion of thefifth embodiment, showing the clip at the distal end thereof; and

FIG. 18 is an end elevation sectional view taken along line 18—18 ofFIG. 17, showing the inclined face of the body portion clip of the fifthembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The objects of the invention are best achieved when the invention takesthe form of the embodiment depicted in the figures. FIGS. 1-11 depict afirst embodiment of the apparatus that is designated generally with thenumeral 10. FIG. 1 depicts the three basic components of the preferredembodiment 10—a nozzle portion 12, a body portion 14 and a triggerportion 16. These portions will be individually discussed as thisdescription continues.

Reference should first be made to FIGS. 2 and 3, which depict apparatus10 as it is packaged, shipped and received by the customer. The customerin this case may be a clinic, a physician or even a patient. Nozzleportion 12 includes outwardly facing threads 22 that are received inbody portion 14, as will be explained in a moment. Extending betweennozzle portion 12 and body portion 14 is an inner sleeve 17 having anenlarged section 19 disposed in the body portion and a reduced section21 disposed in the nozzle portion. Sleeve 17 is sized to fit tightlyinto the nozzle portion. It is fit into the body portion in a tightsliding fit to permit the nozzle portion to be rotated into the bodyportion.

Body portion 14 includes a body 24 with a pair of nozzle portionengagement clips 25 designed to engage the nozzle portion. As shown bestin FIG. 8A, each of the clips has an inwardly extending engagement nib27. The engagement nibs 27 engage the proximal-most threads 22 to holdthe body and nozzle portion together prior to the point that they arefully threaded into each other.

More specifically, the embodiment shown in FIG. 8A has nibs 27, each ofwhich include two faces. The proximal face 27 a extends at about a 90°angle, while the distal face 27 b extends at about a 45° angle. Whenfirst thread 22 is slid over the two clips 25 on the opposite sides ofthe body portion, the resiliency of the clips permits the clips to bendoutwardly to receive the end of the nozzle portion. During this bendingand insertion process, the 90° leading edge of the first thread 22slides over the distal face 27 b of nib 27. Clip 25 snaps back once thefirst thread has cleared the nib. The 90° nib face 27 a complements the90° leading edge of the first thread 22 to prevent the nozzle portionfrom falling out of or being removed from the body portion.

The resiliency of the two clips 25 provides resistance to the nozzleportion being pushed over the 45° face 27 b of nib 27. Thus, duringshipment the nozzle portion will not be sliding in and out of the bodyportion. Once the patient has received the apparatus 10 and wants toprepare it for actuation, he/she can thread the nozzle portion into thebody portion, permitting the 90° face of the next thread 22 to ride overthe 45° face 27 b as clip 25 bends outwardly and snaps back into placeonce the second thread has cleared the 45° face 27 b of nib 27.

Also included in body 24 is a pair of trigger engagement slots 28 thatextend into the end of the body facing trigger portion 16 (see FIG. 1).Trigger engagement slots 28 are disposed 180° across the trigger portionfrom each other; only one of these slots shows in the figures.

FIGS. 1 and 9-11 depict a generally U-shaped safety tab 30 that isfrangibly (or breakably) mounted by three thin webs 33 within one of thetrigger engagement slots 28. Two of the safety tabs 30 may be provided,at the option of the designer, in which case, one safety tab 30 would bepositioned within each of the trigger engagement slots 28. Safety tab 30includes an inwardly-extending chamfered surface 31 (see FIG. 10) thatis designed to be contacted by a corresponding chamfered surface to bedescribed below.

As shown in FIGS. 2-8, threads 40 are included in the distal end of theinner side of body 24. These threads 40 complement threads 22 in nozzleportion 12, so that when the patient is ready to use apparatus 10 toeffect injection, nozzle portion 12 may be rotated into body 24. FIG. 4shows nozzle portion 12 to be threaded about halfway into body portion14. By comparing FIGS. 3 and 4, it can be seen that a drug plunger 66and a drug plug 62 (to be described below) have shifted to the right.With the components in this position the unit is considered primedbecause air has been removed from the front part of nozzle portion 12.FIG. 5 shows nozzle portion 12 to be threaded all of the way into bodyportion 14. In this final threading step a piercing pin 100 pierces agas cartridge 102, and the apparatus is ready for injection. Thisoperation of apparatus 10 will be explained in more detail below.

Again as shown best in FIGS. 1 and 2, trigger portion 16 includes atrigger actuation portion 50 that is in the form of two pads, one oneach side of trigger portion 16. Trigger actuation portion 50 alsoincludes a pair of axially extending trigger members 52 that are alignedwith and extend slightly into trigger engagement slots 28 at 180°positions across the apparatus. Safety tab 30 is frangibly mounted ineach trigger engagement slot 28 by thin webs 33 as mentioned above.

Referring now to FIG. 8, a pair of trigger actuators 53 are shown to bepositioned within trigger members 52. These trigger actuators cooperateto hold a pair of trigger elements 90 in a radially inward position toprevent actuation of the apparatus until the trigger portion 16 is slidforward toward body portion 14. This operation will be described in moredetail below.

FIG. 8 also shows a pair of longitudinally extending ribs 55 that fitinto complementing slots (not shown) in trigger portion 16. These ribs55 also show in FIG. 6A. Immediately rearward of these ribs are a pairof nibs 57 (see FIGS. 3-5, 7 and 8), each of which includes a rearwardinclined face so that trigger portion 16 can be slid onto this rearwardpart of the body.

As identified in FIGS. 3-5, a pair of corresponding trigger nibs 59 and61 define a trigger portion slot (not shown) designed to receive bodynibs 57 on each side of the trigger portion. The trigger nibs 59 and 61are positioned on the inner side of a pair of clips 65 that are cut intothe rear of trigger actuation portion 50. One of these clips 65 appearsin FIGS. 1 and 8. Clips 65 are on opposite sides of the trigger portion,and provide the resiliency needed so that trigger portion 16 can snapinto body portion 14. The complementing inclination of the nib facespermits the trigger actuation portion to slide forward during actuation,but does not permit the trigger portion to be removed from the bodyportion. It thus operates in much the same fashion as clip 25 discussedabove.

FIG. 2 and subsequent figures show the interior, working portions ofapparatus 10. Starting from the right in FIG. 2, an injection orifice 54provides the means by which liquid drug exits apparatus 10 in a defined,high-pressure stream directed into the patient. A liquid drug chamber isdepicted generally at 56, and includes a plastic drug chamber 58 definedby the inwardly facing wall of nozzle portion 12, and a drug storagechamber 51 defined by a glass cartridge 60. Glass cartridge 60 retainsthe liquid drug during storage and shipment and prior to the point thatapparatus 10 is converted to its primed mode with nozzle portion 12being rotated into body portion 14 as described above.

Positioned between drug storage chamber 51 and plastic drug chamber 58is a drug plug 62. Positioned at the rearward or proximal end of drugstorage chamber 51, within glass cartridge 60, is a drug plunger 66. Theresilient material of which drug plunger 66 and drug plug 62 arefabricated is sufficiently impermeable that liquid drug absorption isnot a problem. The material is also inert so that there is no chemicalor biological reaction to the drug. Butyl rubber has both of thesefeatures.

In apparatus 10, glass cartridge 60 is provided to store the liquiddrug. Most conventional plastics are too permeable to allow long-termstorage, so liquid drug is stored in glass cartridge 60 in drug storagechamber 51, and is injected from plastic drug chamber 58, which is theideal function of each material.

Defined in the walls of plastic drug chamber 58, at the forward endtherof, are three drug bypass conduits 64, evenly spaced around theperiphery at 120° increments. These are shown in cross-section in FIG.6C. While three drug bypass conduits 64 are included, any number ofconduits can be utilized. However many conduits are included, theyshould be symmetrically positioned around the periphery of plastic drugchamber 58.

As shown best in FIGS. 2 and 3, bypass conduits 64 includeaxially-extending portions that extend along the length of plastic drugchamber 58. These portions are shown in section in FIG. 6C. As shownbest in FIGS. 2 and 3, bypass conduits 64 also include generallyradially-extending portions, which follow the narrowing of the plasticdrug chamber. As shown in FIG. 6C, the portions of the inward facingnozzle wall extending between bypass conduits 64 actually support drugplug 62 from the sides and from the front (see also FIGS. 4, 5 and 7).The drug bypass conduits 64 are provided to permit liquid drug disposedin plastic drug chamber 58 to flow from the area between drug plunger 66and drug plug 62, and around the drug plug, to displace any air in theforward portion of the plastic drug chamber 58, thus priming theapparatus. During actual injection, liquid drug is driven through bypassconduits 64, out injection orifice 54 and into the patient.

Positioned at the proximal end of sleeve 17 is a seal 68 designed toprevent liquid drug from migrating rearwardly along glass cartridge 60during the priming of apparatus 10 and during injection of drug into thepatient. Seal 68 is normally in the form of an O-ring, but otherconventional seals may alternatively be used.

A gas piston 70 is positioned along the longitudinal centerline ofapparatus 10 in alignment with drug plunger 66 and drug plug 62. Gaspiston 70 extends rearwardly or to the left in the figures to contact agas pressure drive rod 72. Gas piston 70 includes a centrally disposedgas plunger 74 that extends rearwardly into a gas pressure channel 76that passes through the longitudinal center line of gas pressure driverod 72. Each of the gas piston 70 and the gas pressure drive rod 72include cupped portions 78 and 80, respectively, which face each otherin a complementing concave configuration.

Gas pressure channel 76 facilitates the passage of gas pressure throughthe center of the apparatus. A pair of channels 104 extend radiallyoutwardly from gas pressure channel 76 adjacent the rearward end thereofto facilitate the passage of gas pressure from the periphery of the gaspressure drive rod 72 to gas pressure channel 76.

As shown best in FIG. 7, gas piston cupped portion 78 acts to seal gasas it is being expelled out of gas pressure channel 76. The pressurizedgas forces the periphery of cupped portion 78 against the inner surfaceof sleeve 17 to drive gas piston 70 forwardly toward drug plunger 66.The gas pressure is sealed from being exhausted rearwardly by gaspressure drive rod cupped portion 80 that is also forced outwardlyagainst the inner surface of sleeve 17.

Gas pressure drive rod 72 includes a shoulder member 82 that extendsradially outwardly almost all of the way to the inner surface of body24. Shoulder member 82 includes a rearwardly-facing beveled edge 35,which cooperates with chamfered edge 31 of safety tab 30, as will bedescribed in detail below.

Continuing to move rearwardly or to the left in FIGS. 2-5 and 7, body 24can be seen to include a rearward annulus 84 that engages a fixed washerseat 86 having a beveled or angled left side 86 a that in turn holds atrigger ring 88 surrounding gas pressure drive rod 72. A pair of triggerelements 90 are mounted to trigger ring 88, also surrounding gaspressure drive rod 72. As shown best in FIG. 8, a breakaway connectionis provided between trigger ring 88 and trigger element 90, for reasonsthat will be understood as this description continues. Trigger elements90 are identical to each other, disposed 180° apart. Each triggerelement 90 has left and right beveled or angled sides 90 a and 90 b,respectively. The right beveled sides 90 b have a bevel angle thatcomplements that of the left beveled side of fixed washer seat 86 a.That angulation is, in the preferred embodiment, approximately 22degrees.

Continuing along gas pressure drive rod 72, a sliding bushing 92 can beseen. The right hand face 92 a of sliding bushing 92 is beveled orangled to correspond to the angulation of the rearward beveled faces 90a of trigger elements 90, again, typically 22 degrees. Like trigger ring88, sliding bushing 92 fits around gas pressure drive rod 72. This isnot a sealing engagement, however, so a sealing ring 94 is positionedimmediately rearwardly or to the left of sliding bushing 92, alsosurrounding gas pressure drive rod 72. Sealing ring 94 is typically inthe form of an O-ring, but might alternatively take other forms.

Continuing rearwardly or to the left of sealing ring 94, a spacerbushing 96 can be seen surrounding gas pressure drive rod 72 at therearward or left-most end thereof. Like sliding bushing 92, spacerbushing 96 surrounds gas pressure drive rod 72, but does not provide asealing fit, gas sealing being provided solely at sealing ring 94.

This rearward or left-most end of gas pressure drive rod 72 includes anundercut piercing pin receiving seat 98 designed to receive a piercingpin 100. Piercing pin 100 is positioned immediately adjacent a forwardor right-facing end of a gas cartridge 102 so that when leftwardpressure is exerted on piercing pin 100, gas cartridge 102 is pierced,thereby releasing pressurized Nitrogen or other gas from the cartridgeto drive the injection process.

FIGS. 6A, 6B and 6C have been included to show the internal componentsof apparatus 10 in linear cross section. All of the components depictedin these views have already been discussed, except for the four evenlyspaced, generally cylindrical slots that appear in FIG. 6B betweentrigger members 52 and trigger actuator 53. The slots, which have notbeen identified with a numeral, are included merely to facilitateautomated installation of trigger member 92 into trigger portion 16.They serve no real function in the operation of apparatus 10, whichshall now be described.

Operation of the Embodiment of FIGS. 1-11

As mentioned earlier, FIGS. 1-3 depict apparatus 10 in its shipping orstorage configuration. When nozzle portion 12 is fully rotated into bodyportion 14, apparatus 10 is ready for actuation. The conversion processis depicted about half of the way completed in FIG. 4, and completed,ready for injection, in FIG. 5.

It can be seen that during this process of rotating nozzle portion 12into body 24, gas piston 70 exerts a rightward or distal force on drugplunger 66. As the relative positions of the nozzle and body portionschange from the positions of FIG. 3 to those of FIG. 5, drug plunger 66and drug plug 62 move from being disposed within glass cartridge 60 instorage chamber 51 to positions in which the drug plunger is disposedwithin the glass cartridge, but the drug plug is in its forward-mostposition in plastic drug chamber 58, aligned with drug bypass conduits64. The drug plunger and the drug plug move together until this pointbecause the liquid drug is trapped between them.

Once drug plug 62 clears glass cartridge 60, liquid drug can flow aroundthe drug plunger via drug bypass conduits 64 and dribble out injectionorifice 54. This removes any air in the front of the plastic drugchamber 58 and primes apparatus 10 for activation. Prior to actuation,however, gas cartridge 102 must be pierced. This is done by completelythreading the nozzle portion 12 into the body portion 14, as depicted inFIG. 5.

However, gas is not yet released to the body portion or the nozzleportion because sealing ring 94 prevents gas from passing beyond thatpoint in the apparatus. Specifically, gas pressure is prevented fromflowing into radial channels 104 as long as the sealing ring is disposedrearwardly of the radial channels. Radial channels 104 are also blockedby sliding bushing 92, but because this is not a sealing contact, thisdoes not prevent the passage of gas pressure.

As rotation of nozzle portion 12 into body portion 14 is completed,beveled or chamfered edge 35 of shoulder 82 contacts chamfered edge 31of safety tab 30. The complementing beveled faces force the safety tabaway from the apparatus, breaking the connection at thin webs 33. Thisdisengages the safety tab from the apparatus, permitting it (or “them”if there are two safety tabs) to fall out of trigger engagement slot 28.This clears a space for trigger member(s) 52 to enter the triggerengagement slot(s) 28.

Once rotation of nozzle portion 12 into body portion 14 is complete asdepicted in FIG. 5, apparatus 10 is primed and ready for actuation. Atthis point, gas cartridge 102 has been pierced by piercing pin 100,although the gas pressure is still contained by sealing ring 94. Liquiddrug is disposed in plastic drug chamber 58 adjacent injection orifice54, forward of drug plunger 66 and forward and rearward of drug plug 62.In fact, some of the drug may have actually dribbled out of the drugorifice, simply to ensure that any remaining air has been completelyremoved from plastic drug chamber 58.

Until the apparatus is actuated, the pair of trigger actuators 53 holdthe two trigger elements 90 against gas pressure drive rod 72. Aradially-outward force is being exerted on the trigger elements as aresult of the forward thrust on sealing ring 94 and the angulation ofthe interface between sliding bushing 92 and trigger elements 90 at 92 aand 90 a respectively, and between fixed washer 86 and trigger elements90 at 86 a and 90 b, respectively. The forward thrust is, of course,provided by the gas pressure being exerted on the sealing ring becauseof the piercing of the gas cartridge.

In order to effect injection, trigger actuation portion 50 is slid tothe right or in a forward direction. By sliding trigger actuationportion 50, trigger members 52 are permitted to move into triggerengagement slots 28. Trigger actuators 53 therefore no longer holdtrigger elements 90 radially inwardly, and the gas pressure beingexerted on sealing ring 94 and sliding bushing 92 causes the slidingbushing to push to the right so that the complementing angled facescause the trigger elements to be shifted outwardly to the gap formed bythe removal of the trigger actuators, as shown in FIG. 7. Theradially-outward force on the trigger elements once the triggeractuators have moved is sufficient to break the connection betweentrigger ring 88 and trigger elements 90 depicted in FIG. 8. Once triggerelements 90 are moved radially outwardly, sliding bushing 92 continuesto slide to the right. Along with the sliding of the sliding bushing,sealing ring 94 moves to the right as well, past radial channels 104.This permits gas under pressure to be directed along the interfacebetween spacer bushing 96 and gas pressure drive rod 72, thereby passinginto radial channels 104 and gas pressure channel 76. Gas thus rushesthrough gas pressure channel 76 and gas pressure drive rod 72 and intothe interior of body 24. This forces gas plunger 74 out of gas pressurechannel 76, exerting gas pressure on gas piston cupped portion 78. Thisforces the cupped portion against inner sleeve 17, sealing the interfacebetween these components and driving gas piston 70 to the right.

As gas piston 70 is driven to the right, it forces drug plunger 66forwardly, forcing liquid drug from glass drug storage chamber 51,through drug bypass channels 64, and out through injection orifice 54,into the patient.

The embodiment of FIGS. 1-11 is designed for subcutaneous injection.Therefore it does not include an intradermal spacing feature. Such afeature is included in the embodiment depicted in FIG. 12. Thisvariation will now be described.

Intradermal Injection Embodiment of FIG. 12

FIG. 12 depicts a second embodiment of the present invention, which isindicated generally at the numeral 110. This embodiment 110 is virtuallyidentical to apparatus 10 except that nozzle portion 112 includes anintradermal spacing section 118. Thus, it can be seen that the injectionorifice 154 is spaced away from the skin of the patient duringinjection. This results in the liquid drug being directed into butnormally not entirely through the skin of the patient.

It can be seen in FIG. 12 that, other than dimensional differences andthe provision of intradermal spacing section 118, the nozzle portion112, body portion 114 and trigger portion 116 are essentially identicalto corresponding portions of apparatus 10. The size of the injectionorifice and the volume of liquid drug are slightly different whencomparing apparatus 110 and apparatus 10, but those parameters are up tothe product designer and the physicians involved in effecting theinjections.

Embodiment of FIG. 13

FIG. 13 depicts another embodiment that is identical to apparatus 10 ofFIGS. 1-11, except that it includes a pair of ball bearings 290 in placeof trigger elements 90 and trigger ring 88. Given the sphericalconfiguration of balls 290, they include inclined surfaces (sometimesreferred to herein as angled faces) which will cooperate with thecomplementing inclined surfaces 292 a of sliding bushing 292 and 286 aof fixed washer 286 in the same fashion as previously described withrespect to apparatus 10.

It may be desirable in some applications to include more than two ballbearings; it may also be desirable to include some sort of conventionalball bearing cage (not shown in the figures).

Embodiment of FIG. 14

FIG. 14 is a fragmentary sectional view showing an embodiment thatincludes a smaller O-ring seal than seal ring 94 of apparatus 10 ofFIGS. 1-11. This smaller seal, identified at 394, is provided in orderto reduce the amount of axial force exerted on the seal ring and thetrigger element 390. This embodiment of FIG. 14 is actually thepresently preferred mode of practicing the invention.

The embodiment of FIG. 14 is identical in most respects to apparatus 10,except that it includes a spacer bushing 396 that has a pair of steps toaccommodate the smaller seal 394. A second seal 397, typically in theform of an O-ring, is included in spacer bushing 396 to prevent pressurefrom leaking past the interface between body portion 316 and the spacerbushing. Sliding bushing 392 is generally L-shaped to complement theconfiguration of spacer bushing 396 and the fit of seal 394. A triggerelement 390 is shown having angled faces to complement those of slidingbushing 392 and fixed washer 386, as with the prior embodiments. Atrigger ring may also be included to facilitate the assembly of triggerelements 390, but it has not been depicted for purposes ofsimplification.

In operation, after gas cartridge 302 is pierced, forward axial pressureis exerted on seal 394, but because the seal has a smaller surface thanseal ring 94, the forward force is less than with apparatus 10. Thisresults in less force on trigger elements 390, which reduces the outwardbias on the trigger elements prior to actuation of the unit. The bias issufficient, however, to break any connection between a trigger ring (notshown) and the trigger elements. In other respects, the construction andoperation of this embodiment is identical to that of apparatus 10.

Embodiment of FIGS. 15-18

FIGS. 15-18 depict another embodiment that includes a variation of thesystem for engaging nozzle portion 412 and body portion 414. As shownbest in FIGS. 15 and 16, a pair of notches 423 and 427 are provided inthreads 422 of nozzle portion 412. As shown in FIG. 16, each notch 423and 427 includes a 90 degree face 423 a and an angled face 423 b.Complementing these faces, as shown in FIG. 18, is a 90 degree face 425a and an angled face 425 b in clip 425. Thus, when nozzle portion 412 isonly partially threaded onto body portion 414 for shipping, the naturalresiliency of clip 425 enables angled clip face 425 b to ride overangled slot face 423 b. When threaded beyond that point, 90 degree faces423 a and 425 a are in abutment, preventing the nozzle and body portionsfrom threading off of each other. When the nozzle and body portions areentirely threaded onto each other, such as when the gas cartridge hasbeen pierced and the apparatus is ready for actuation, a corresponding90 degree face of slot 427 engages 90 degree face 425 a of clip 425 toprevent the nozzle and body portions from being even partially threadedoff each other. This ensures that when the trigger mechanism isactuated, the nozzle and body portions will be fully engaged. It alsoprevents any disassembly of the unit after the gas cartridge has beenpierced. This body and nozzle engagement system of FIGS. 15-18 ispresently considered the best mode of engaging the nozzle and bodyportions.

Other changes and modifications of the present invention can be madewithout departing from the spirit and scope of the present invention.Such changes and modifications are intended to be covered by thefollowing claims.

I claim:
 1. A needle-free injection system comprising: a nozzle portionhaving a glass wall defining a drug storage space, and an injection walldefining a drug injection space, the injection wall being aligned withthe glass wall; a body portion mounted to the nozzle portion such thatrelative axial movement may be effected between the portions; aninjection orifice defined at the forward end of the injection space; adrug plunger defining rearward end of the storage space, with aplurality of drug bypass conduits defined between the forward end of thedrug injection space and the drug plunger; a drug plug initiallydisposed between the storage space and the injection space, and beingdisplaceable into the injection space adjacent the bypass conduits; anda pierceable gas cartridge for providing injection power to the drugplunger.
 2. The system of claim 1, further comprising a gas pistonextending toward the drug plunger to convey injection power between thegas cartridge and the drug plunger, wherein the none and body portionsinclude complementing threads such that when the portions are threadedinto each other, the gas piston exerts a force on the drug plunger. 3.The system of claim 1 wherein the nozzle and body portions includecomplementing threads, and the threads of at least one of the portionsincludes a notch with an abutment face and an angled face, the other ofthe portions including a complementing nib having an abutment face andan angled face to facilitate threaded engagement but to preventdisengagement when the portions are at least partially threaded intoeach other.
 4. The system of claim 3, further comprising a second notchincluded in the threads of at least one of the portions, the secondnotch having an abutment face and an angled face, the other of theportions including a complementing nib having an abutment face and anangled face to facilitate threaded engagement but to preventdisengagement when the two portions are substantially fully threadedinto each other.
 5. The system of claim 1, further comprising an innersleeve extending between the nozzle and the body portions.
 6. The systemof claim 5, further comprising a seal disposed at a forward end of thesleeve to prevent drug from migrating rearwardly during the injectionprocess.
 7. The system of claim 5 wherein the sleeve includes a largerportion and a smaller portion, the larger portion including aninwardly-facing sleeve wall and wherein the gas piston includes anexpanded portion extending to and in sealing relation with the sleevewall.
 8. The system of claim 1, wherein the bypass conduits includeaxial-extending and radial-extending portions.
 9. A needle-freeinjection system comprising: a nozzle portion having a glass walldefining a drug storage space, and an injection wall defining a druginjection space, the injection wall being aligned with the glass wall;an injection orifice defined at a forward end of the injection space; adrug plunger defining rearward end of the storage space; a pierceablegas cartridge for providing injection power to the system; a gaspressure rod positioned rearwardly of and coaxial with the drug plunger,the gas pressure rod defining an axially extending gas channel and atleast one radially extending gas channel; and a seal disposed adjacentthe gas pressure rod positioned to receive gas pressure when the gascartridge has been pierced, the gas pressure exerting a forward force onthe seal, the seal being slidable between positions rearward and forwardof the radial gas channel, the seal sealing gas pressure from passingforwardly of the seal, such that when the seal is disposed forwardly ofthe radial gas channel gas pressure can pass through the radial channeland into the axial channel and be directed forwardly to drive the drugplunger forwardly.
 10. The system of claim 9, further comprising: atrigger member disposed forwardly of the seal and being positioned andconfigured such that when forward force is exerted on the angled face,the trigger member is biased radially outwardly; and a trigger actuatordisposed radially outwardly of the trigger member to hold the triggermember in place against the outward bias exerted when the gas cartridgeis pierced, so that when the system is actuated and the trigger actuatoris moved away from the trigger member, a path is cleared for the triggermember to move radially outwardly.
 11. The system of claim 10, furthercomprising: a sliding member disposed between the seal member and thetrigger member and having a forward face in contact with the triggermember, the forward face of the sliding member being angled tocomplement the trigger member face so that when the gas cartridge ispierced and forward force is exerted on the seal ring, forward force isconveyed to the sliding member, and the angled face of the slidingmember and the trigger member cooperate to exert a radially outwardforce the trigger member.
 12. The system of claim 9 wherein the seal ismounted to move forwardly with the sliding member so that when thetrigger actuator is moved to facilitate radially outward movement by thetrigger member, the seal slides forward with the sliding member to aposition where the seal is forward of the radial gas channel, therebyfacilitating a flow of pressure from the gas cartridge through theradial gas channel and into the axial gas channel to drive the drugplunger forwardly, driving drug from the injection space out theinjection orifice.
 13. The system of claim 9, further comprising anotherangled face disposed forwardly of the trigger member, and wherein thetrigger member includes a second angled face disposed against such otherangled face to further facilitate exertion of a radially outward forceon the trigger member when forward force is exerted by the slidingmember and the seal.
 14. The system of claim 9 wherein the triggermember includes a beveled face that complements the forward, angled faceof the sliding member.
 15. The system of claim 9 wherein the triggermember includes at least one ball that contacts and rides on the forwardangled face of the sliding member.
 16. The system of claim 9, furthercomprising a body portion positioned rearwardly of and coaxial with thenozzle portion, the nozzle and body portions including threads tothreadably engage each other, and wherein an engagement clip is mountedto at least one of the body and nozzle portions to engage the threads ofthe other portion.
 17. A needle-free injection system comprising: anozzle Portion having a glass wall defining a drug storage space, and aninjection wall defining a drug injection space, the injection wall beingaligned with the glass wall; a body portion mounted to the nozzleportion such that relative axial movement may be effected between theportions; an injection orifice defined at the forward end of theinjection space; a drug plunger defining a rearward end of the storagespace, with a plurality of drug bypass conduits defined between theforward end of the drug injection space and the drug plunger; apierceable gas cartridge for providing injection power to the drugplunger.
 18. The system of claim 17, further comprising a gas pistonextending toward the drug plunger to convey injection power between thegas cartridge and the drug plunger, wherein the nozzle and body portionsinclude complementing threads such that when the portions are threadedinto each other, the gas piston exerts a force on the drug plunger. 19.The system of claim 17 wherein the nozzle and body portions includecomplementing threads, and the threads of at least one of the portionsincludes a notch with an abutment face and an angled face, the other ofthe portions including a complementing nib having an abutment face andan angled face to facilitate threaded engagement but to preventdisengagement when the portions are at least partially threaded intoeach other.
 20. The system of claim 19, further comprising a secondnotch included in the threads of at least one of the portions, thesecond notch having an abutment face and an angled face, the other ofthe portions including a complementing nib having an abutment face andan angled face to facilitate threaded engagement but to preventdisengagement when the two portions are substantially fully threadedinto each other.
 21. The system of claim 17, further comprising an innersleeve extending between the nozzle and the body portions.
 22. Thesystem of claim 21, further comprising a seal disposed at a forward endof the sleeve to prevent drug from migrating rearwardly during theinjection process.
 23. The system of claim 21 wherein the sleeveincludes a larger portion and a smaller portion, the larger portionincluding an inwardly-facing sleeve wall and wherein the gas pistonincludes an expanded portion extending to and in sealing relation withthe sleeve wall.
 24. The system of claim 17, wherein the bypass conduitsinclude axial-extending and radial-extending portions.